Fossil assemblages are groups of fossils from different dinosaurs. For example, one assemblage found in the sandstones of the Gobi Desert is of a carnivorous Velociraptor intertwined with a herbivorous Protoceratops. The Velociraptor’s clawed feet were attached to its prey’s throat and belly, while the Protoceratops’ jaws had trapped the arm of the predator. This assemblage suggests the struggling dinosaurs, predator and prey, died together as a massive sandstorm overcame them.

In fifteen sites in Montana, major fossil assemblages have been found: the teeth of the carnivorous dinosaur Deinonychus found in association with the fossil remains of herbivorous dinosaur Tenontosaurus. Dinosaur teeth were continually shed, as new ones grew in, and vigorous biting could have increased tooth loss. In fact, there is lack of Deinonychus teeth found with the remains of other dinosaurs, leading paleontologists to conclude that the Tenontosaurus was the favorite prey of this predator.